The present invention generally relates generally to procedures for wireless communication networks, and more particularly, to a method of avoiding unnecessary transmission of paging messages over the air interface.
Cellular networks were originally developed to primarily provide voice services over circuit-switched networks. The introduction of packet-switched 2.5G and 3G networks enables network operators to now provide data services, as well as voice services. Eventually, network architecture is expected to evolve toward all-IP networks providing both voice and data services. However, network operators have a substantial investment in existing infrastructure and are expected to migrate gradually to an all-IP network architecture and to use their existing infrastructure whenever possible. At the same time, network operators recognize that there is a demand for high rate packet-data services.
In order to provide high-rate packet data services, network operators may deploy hybrid networks, where a high data rate (HDR) network is overlaid on an existing circuit-switched or packet-switched network as a first step in the transition to an all IP-based network. One example of a hybrid network combines an IS2000 radio access network to provide voice and low-rate packet data services, with an IS855 radio access network to provide high-rate packet data services. When the mobile station is monitoring the packet data channel in the IS-856 network, the IS2000 network may need to page the mobile station to connect an incoming voice call. Conventionally, the mobile station would be required to periodically transition to the IS2000 network to monitor the common channels while operating within the IS856 network.
The IS856 standard has been recently amended to include a protocol known as the circuit service notification protocol (CSNP). The CSNP enables the IS2000 network to send signaling messages to the mobile station via the IS856 network so that the mobile station no longer needs to periodically return to the IS2000 network to receive circuit services notifications. When the mobile station receives an A1 paging request from the IS856 access network, the mobile station switches to a IS2000 carrier and transmits a page response message. The MSC will typically include a TAG information element in the A1 paging request sent to the IS856 access network. The TAG information element is normally used in the IS2000 network to match a page response from the mobile station with the corresponding A1 paging request. However, the TAG information element is not transmitted to the mobile station and there is currently no way to transmit the TAG IE from the IS 856 access network to the IS2000 base station. Consequently, the IS2000 base station will process the page response as an unsolicited page response. When an A1 page response is forwarded to the MSC, the MSC will not be able to correlate the A1 paging response to the original A1 paging request and may reject or ignore the A1 page response.
One way to handle unsolicited paging response messages at the MSC would be to send the A1 paging request to the IS2000 base station as well as the IS856 access network even though the mobile station is known to be currently operating in the IS856 access network. This solution, however, wastes valuable air interface resources for redundant page messages that will not be received by the mobile station. Another possible solution would be to modify the MSC to handle unsolicited page responses without the need for a TAG IE to correlate the page response with a paging request. However, implementing changes in the MSC can be complicated and are not desirable.